Geochemical prospecting method



Nov. 16, 1943. 5. K ss GEOCHEMICAL PROSPECVTING METHOD Filed Dec. 9, 1939 MM CZ. K1214 INVENTOR.

BYL

Z? J Amy.

Patented Nov. 16, I943 VGEOCHEMIOALI PROSPECT-ING METHOD Stephen A. Kiss, New York, N. Y.', assignor to Standard Oil Develo poration of Delaware pment Company, a cor- Afi plication December 9, 1939, Serial No. 308,382

4 Claims.

The present invention relates to prospecting for oil, gas and other carboniferous deposits by collecting samples of soil gas in the area to be explored and analyzing these gases for hydrocarbons and other gases indicative of such deposits, such as hydrogen and carbon monoxide.

In U. S. Patent Number 1,843,878 this general 1 method of prospecting has been described. The

patentee discloses a deviceto be used for sucking gas samples from shallow boreholes. In actual practice, the gas samples so recovered are highly diluted with soil air whereby the quantitative determination of hydrocarbons therein is rendered extremely diflicult.

It has now been found that much richer samples of soil gas can be obtainedJoy treating the earth with chemical agents which serve to disenage gases which are so intimately associated with the soil as to be inseparable therefrom by ordinary suction. Most electrolytes have some utility for this purpose, but there are some which are prominent because they bring about the liberation of exceptional quantities of gas from the soil. Typical of these latter areacids, particularly hydrochloric and sulphuric which may be used in any desired concentrations and are preferably used in dilute form. Organic acids may be employed'as well as inorganic. Strong alkalis also function satisfactorily in this respect. Wetting agents, such as sulphonic acids obtained from the acid treatment of mineral oils, alkylated naphthalene sulphonic acids, particularly isopropyl naphthalene sulphonic acid, sulfonated fatty acids and esters thereof, aminesand amides of various typ s, particularly those produced by the reaction of long chain fatty acids with alkylolamines, and other common wetting agents may be employed with advantage. y

The present invention may be practiced '1 various ways. Where soil gassamples are collected at the surface the ground is wetted down with the treating agent andsuction is then applied to the ground, usually by fixing in the ground over the wetted area a bell-like receptacle. to which is attached a suction pump. When the gas sample 'is collected at .a substantial depth the present method is carried out with the apparatus and in the manner indicated in'the accompanying drawing in which the single figure is a vertical section through a borehole which is prepared for the practice of the-present invention.

Referring to the drawing in detail, numeral 'ldesignates the earth in which is a borehole 2 substantially filled with a fluid 3 which is usually an aqueous slurry of clay. Fixed in the earth around the borehole is a bell-like member I the edges of which are embedded in the earth. Protruding through the wall of receptacle 4 is a pipe 5 which is of a suiilcient length to extend to the bottom of the hole 2 and is provided at its outer end with a valve 6 and a funnel I. ReceptacleA is also provided with a drawoff pipe 8 which is connected to a pump and a gas-holding receptacle, both of which are common in this art and are, therefore, not shown.

In practicing the method of the present invention with the arrangement shown in the drawing, a borehole is dug to any suitable depth, usually exceeding four feet and preferably greater than ten feet. In practice, these boreholes are often made fifty feet in depth. The drilling of this hole is naturally accomplished with the aid of a drilling fluid such as aqueous mud so that when the hole is finished it is full of drilling fluid.

. The bell-like member 4 is then set in place with the tube 5 extending substantially to the bottom of the hole. Acid is then poured in funnel I with the valve 6 open. Generally, several gallons of dilute acid, or any other agent which-may be employed, are introduced. When acid itself is employed, gas is immediately developed in fairly large quantities and is pumped ofl' through pipe 8. When alkalies are used it is preferable to leave the system closed for several-hours, sometimes as long as a few days, before beginning to pump ofi'the gas. If corrosion inhibitors are added to the acid the generation ofgas is also slowed ,down. The sample of gas' so collected is then subjected to the usual drying and carbon dioxide removing step and is analyzed for hydrocarbons or hydrogen, or carbon monoxide or any other gaseous constituent which may be selected as the indicator for subsurface deposits. I

When the sample of gas is collected in the manner just described it is diluted considerably with soil air. In order o avoid this dilution it is desirable to first pump off what gas will come off before admitting the treatingagent. Thisfirst as is discarded and the only gas collected is that liberated by the action of the treating agent.

The nature and objects of the present invention having been thus described and illustrated, what is claimed as new and useful and is desired to be secured by Letters Patent is:

1. In the method of geochemical prospecting l for carboniferous deposits in which soil gas is recovered from the earth in place and analyzed for constituents indicativeoi' the proximity of.

such deposits, the step of preliminarily treating the soil in place with a water soluble organic wetting agent.

2. A method according to claim 1 in which the agent employed is an organic suiphonic acid.

3. In the method'of geochemical prospecting for subsurface petroliferous deposits in which soil gas is recovered from the soil and analyzed for constituents indicative of the proximity of t such deposits, the step of preliminarily treating the soil with a water soluble organic wetting agent, whereupon such constituents not otherwise readily removed from the soil are freed therefrom for collection and analysis.

4. A method according to claim 3 in which the agent'employed is an organic sulfonic acid.

STEPHEN A. KISS. 

